1. Field of the Invention
The present invention relates to a method of high speed recording of images and of information associated with the images by means of a motion picture camera for high speed shooting equipped with an image pulse generator and also to an apparatus for implementing the method.
2. Discussion of Background
At present, motion picture cameras for high speed shooting using claws or rotary prisms are equipped with or are suitable for being equipped with light emitting diodes (LEDs) or alphanumeric character displays for writing information on the motion picture film. FIG. 1 of the accompanying drawings shows a prior art motion picture camera 1 for high speed shooting. A box 2, which is conventionally disposed adjacent to the camera 1, contains electronic circuits which receive information from one or more information sources 3a, 3b, ..., 3n, for example an IRIG B time source or clock, and speed, pressure, temperature, etc. sensors providing information or data in analog form or in serial or parallel digital form. If necessary, said information may be decoded in the box 2 and then recoded in a form that is suitable for being written on the motion picture film.
At present, there are two known methods of writing information on film. The first method consists in recording the information on marginal tracks of the motion picture film 4 by means of an electro-optical device 5 placed adjacent to a loop of motion picture film in the camera 1, as shown in FIG. 2. This method is similar to the method of recording image pulses from a camera and from a time base in an auxiliary recorder. The portion of the film which is used as the recording medium is a portion which is running at a steady speed. One to four LEDs are conventionally used for writing information to the marginal tracks of the motion picture film. A track 6 may be written on either side of each of the rows of perforations or sprocket holes 7 of the motion picture film 4, as shown in FIG. 3.
The second known method consists in writing information on the motion picture film 4 in binary form or in binary coded decimal (BCD) form, etc. as a matrix as shown in FIGS. 5 and 6 and at the bottom of FIG. 7, or else in the form of characters in the clear as shown at the top of FIG. 7, for example by means of an alphanumeric character display 8 and an optical system comprising reflector elements 9 and 11 as shown in FIG. 4 In this case, the information may be written on the motion picture film 4 either within each image frame or to one side thereof (FIG. 3), or in the gap between two successive image frames (FIG. 5) for discontinuous motion cameras, or else to one side of the images per se in a zone lying between the images and one of the rows of sprocket holes 7 of the film 4 (FIG. 6) or else between successive frame sprocket holes 7 when using a 16 mm motion picture film (FIG. 7).
Prior art methods of writing information on a motion picture film in a high speed camera suffer from various drawbacks.
In particular, the amount of information which can be written on marginal tracks in the form of serial bits is limited, at high speed, by the minimum bit length (0.2 mm) and by possible blurring effects which give rise to difficulty in reading back the information written on the film.
The writing of matrices or characters in the clear in the image frames, between successive frames, or between the images per se and the sprocket holes of the film all limit the area of film available for images per se. When using matrices or characters in the clear, each camera must be equipped with electro-optical write devices which, given the high speed at which the film is running, are expensive and difficult to install, and in particular are difficult to retrofit to existing equipment. In addition, the writing of matrices or characters in the clear between two successive film sprocket holes or in the gap between two image frames is not always compatible with said information being transferred when the film is duplicated using standard means.
In any event, the amount of information which can be written on film in association with each image frame is relatively limited.
When the information on the motion picture film is being examined by means of a film reader, it is easier to read characters which are in the clear than it is to read serial bits or encoded matrices However, in all cases the manual transfer of such information via a keyboard to enter said information into a memory of the film reader is a long and tedious process. With some prior film readers, it is possible to examine the information on the film automatically; however this requires equipment which is expensive and often complex for reading the serial bits, the encoded matrices, or the characters in the clear. Further, each type of writing requires special equipment and software specific to the location of the information on the film, to the kind of code used, to the sizes of the bits, etc.
The present invention therefore seeks to provide a method and apparatus enabling images and information associated with the images to be recorded at high speed without it being necessary to equip the motion picture camera used for shooting with expensive and complex electro-optical elements for recording said information, and without it being necessary to equip the film reader with expensive and complex electro-optical elements for reading back the information associated with the images.
The present invention also seeks to provide a method and apparatus making it possible, if so desired, to record a greater number of additional data items with each motion picture film image, even when using cameras operating at very high rates.